Fix emulator instance in perf tests.

Author: vhristov5555

tests/perf/start_time.py

@@ -180,7 +180,7 @@ def test_start_time(self, demo, config, device_name, device_id, first_start, sec
             start_time_expected = first_start
             second_start_expected = second_start
             Adb.reboot_device(self.DEVICE_ID)
-            emulator.wait(self.DEVICE_ID)
+            Emulator.wait(self.DEVICE_ID)
 
         start_time_actual = 0
         second_start_actual = 0